FLOW CHART AND PSEUDO CODE

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John Beasley
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1 FLOW CHART AND PSEUDO CODE

2 Flowchart A Flowchart is a pictorial representation of an algorithm. The First flowchart is made by John Von Newman in It is a symbolic diagram of operation sequence, dataflow, control flow and processing logic in information processing. The symbol used are simple and easy to learn. It is a very help full tool for programmers and beginners.

3 The Flowchart (Dictionary) A schematic representation of a sequence of operations, as in a manufacturing process or computer program. (Technical) A graphical representation of the sequence of operations in an information system or program. Information system flowcharts show how data flows from source documents through the computer to final distribution to users. Program flowcharts show the sequence of instructions in a single program or subroutine. Different symbols are used to draw each type of flowchart.

4 The Flowchart A Flowchart shows logic of an algorithm emphasizes individual steps and their interconnections e.g. control flow from one action to the next

5 Purpose of flowchart Provide Communication. Provide an overview. Show all elements and its relationship. Quick method of showing program flow. Check program logic. Facilitate coding. Provide program revision. Provide Program documentation.

6 FLOWCHART A flow chart is a graphical or symbolic representation of a process. They are basically used to design and document complex processes to help the viewers to visualize the logic of the process so that they can gain a better understanding of the process and find flaws, bottlenecks, and other less-obvious features within it. Start and end symbols also known as the terminal symbol is always the first and the last symbol in a flowchart. Generic processing step also called an activity is represents instructions like add a to b, save the result. Input/ Output symbols are represented as a parallelogram and are used to get input from users or display the results to them. A Conditional or decision symbol is used to depict a Yes/No question or True/False test. Labeled connectors represented by an identifying label inside a circle are used in complex or multi-sheet diagrams to substitute for arrows.

7 Symbols used in flowchart All symbols are of different shape and size. All have specific meaning and use. The ANSI ( American National Standard Institute) group categories symbols in 3 types basic, specialized and additional symbols. These institution and standardized these basic symbols for use.

8 BASIC SYMBOLS Terminal Symbol = for start and stop. INPUT and OUTPUT = Any function of input and output data. Processing = An arithmetic and data movement instruction. Shows mathematical calculation and logic operations.

9 SYMBOLS Decision = Diamond indicate decision point in the program flow. IT may have 2 way branch or 3 way also. Flow Lines = A Straight line between two boxes shows the path of logic flow in the program. An arrow head on the top of the line shows the direction of the flow, data from top to bottom and left to right. Connectors = 2 small circles are used to connect separated portions of a flowchart without drawing lines between the parts. One connector indicated where the flow breaks off the other where it resumes.

10 Flowchart Symbols Basic

11 Flowcharts for three constructs

12 Advantages of flowchart. Communication. Effective analysis. Proper documentation. Efficient coding. Proper debugging. Efficient program maintenance. Easy and clear presentation.

13 Advantages of Flowcharts A flowchart is a diagrammatic representation that illustrates the sequence of steps that must be performed to solve a problem. They are usually drawn in the early stages of formulating computer solutions to facilitate communication between programmers and business people. Flowcharts help programmers to understand the logic of complicated and lengthy problems. They help to analyze the problem in a more effective manner Flowchart is also used for program documentation. Flowchart can be used to debug programs that have error(s).

14 Limitation of flowchart Complex logic. Drawing is time consuming. Alteration and modification. Redrawn many times. Difficult to draw and remember. Reproduction ( replica ). Technical detail.

15 Limitations of using Flowcharts Drawing flowcharts is a laborious and a time consuming activity. Flowchart of a complex program becomes, complex and clumsy. At times, a little bit of alteration in the solution may require complete re-drawing of the flowchart Essentials of what is done may get lost in the technical details of how it is done. There are no well defined standards that limits the details that must be incorporated in a flowchart

19 PSEUDOCODE It is a form of structured English that describes algorithms. It facilitates the designers to focus on the logic of the algorithm without getting bogged down by the details of language syntax. Pseudocode is a compact and informal high-level description of an algorithm that uses the structural conventions of a programming language. It is meant for human reading rather than machine reading, so it omits the details that are not essential for humans. Such details include keywords, variable declarations, system-specific code and subroutines. It is commonly used in textbooks and scientific publications for documenting algorithms, and for sketching out the program structure before the actual coding is done. This would help even the non-programmers to understand the logic of the designed solution. There are no standards defined for writing a pseudocode because a pseudocode is not an executable program. Flowcharts can be considered as a graphical alternative to pseudocode, but are more spacious on paper.

20 Pseudo code First produce a general algorithm (one can use pseudo code) Refine the algorithm successively to get step by step detailed algorithm that is very close to a computer language. Pseudo code is an artificial and informal language that helps programmers develop algorithms. Pseudo code is very similar to everyday English.

21 Pseudocode Pseudocode is an informal description of an algorithm English-like statements that require less precision than a formal programming language. Allows the designer to focus on the logic of the algorithm without being distracted by details of language syntax. A good pseudocode algorithm should be independent of, but easily translated into, any formal programming language.

22 Pseudocode Control Structures Sequence control structures Instructions are performed linearly Conditional control structures A choice/selection is made between multiple courses of action Looping/iteration control structures Enables repeating instructions within the algorithm A test condition determines when the repetition ends

23 Pseudocode Control Structures Selection and conditional 1. if (condition) then 2. statement endif If the (condition) is TRUE then statements between THEN and ENDIF are executed once

24 Two-way decision 1. if (condition) then 2. statement else 5. statement n endif If the (condition) is TRUE then statements between THEN and ELSE are executed once If the (condition) is FALSE then statements between ELSE and ENDIF are executed once

25 LOOP For Loop Used to implement statements that needs to be repeated a fixed number of times. 1. for i 1 to n 2. Statement next i i is the index or counter that starts with some value and increases by one every time through the loop until it reaches the given maximum value

26 Repeat until Repeat Loop Used to implement statements that needs to be repeated until the condition becomes TRUE. 1. repeat 2. Statement until (condition)

27 While LOOP While Loop Used to implement statements that needs to be repeated while the condition is TRUE. 1. while (condition) 2. Statement endwhile

28 Pseudocode for three constructs

29 Advantages Converting a pseudo code to a programming language is easier than converting a flow chart to programming language. It is easier to modify the pseudo code of a program logic when program modification is necessary. Required less time and effort than flow chart.

30 Limitations A graphical representation of program logic is not available. There are no standard rules to follow in using pseudo code. It is very difficult for beginners.

31 Example: Write a pseudocode to calculate the weekly wages of an employee. The pay depends on wages per hour and the number of hours worked. Moreover, if the employee has worked for more than 30 hours then he gets twice the wages per hour, for every extra hour that he has worked. Read hours worked Read wages per hour Set overtime charges to 0 Set overtime hrs to 0 If hours worked > 30 then Calculate overtime hrs = hours worked 30 Calculate overtime charges =overtime hrs * (2 * wages per hour) Set hours worked = hours worked - overtime hrs ENDIF Calculate salary = (hours worked * wages per hour) + overtime charges Display salary End Variables: hours worked, wages per hour, overtime charges, overtime hrs, salary

depicts pictorially schematic representation of an algorithm document algorithms. used in designing or documenting

depicts pictorially schematic representation of an algorithm document algorithms. used in designing or documenting Definition A flowchart depicts pictorially the sequence in which instructions are carried out in an algorithm. A flowchart is a schematic representation of an algorithm or a stepwise process, showing the